1. Field of the Invention
This invention generally relates to a continuously varying mechanical transmission generally having two sets of planetary gears. The transmission of the present invention has a first planetary group generally comprising a control sun, a driven sun and planet gears and a secondary planetary group generally comprising a load gear, planetary gear and a ring gear arranged and interconnected to provide an easily controllable reduction of ratio between in-lined driving and driven shafts. Each of the planet gears of the first planetary group, being paired and meshed with each other, interact with the control sun and driven sun to permit the reaction forces in all the components to react or rotate simultaneously.
2. Description of the Relevant Art
There has been a substantial need for simplifications and reductions in the cost in manufacturing and maintaining transmission systems. Fluid transmissions (as in U.S. Pat. No. 4,213,352 filed by H. Crawford on Mar. 14, 1978 and issued July 22, 1980; and in U.S. Pat. No. 4,455,891 filed by G. Freeman on Apr. 13, 1981 and issued June 26, 1984) have been developed to provide desirable features. However, fluid transmissions require constant attention and maintenance, especially the need to frequently adjust and replace brake bands associated with such transmissions. More specifically, when used in conventional automobiles, the fluid transmission's torque aversion mechanism is not automatically activated, but require a depression of an accelerator pedal.
The employment of gears of various configurations and arrangements have been provided to simplify continuously variable automatic transmissions as in U.S. Pat. No. 3,015,967 filed on Feb. 8, 1956 by C. Bancroft and issued Jan. 8, 1962; U.S. Pat. No. 3,302,488 filed on Feb. 5, 1963 by F. Graff and issued Feb. 7, 1967; U.S. Pat. No. 3,114,273 filed in May 15, 1962 by B. Boggs and issued Dec. 17, 1963; and U.S. Pat. No. 4,327,604 filed on Sept. 27, 1979 by R. Evans and issued May 4, 1982. The above-mentioned systems are cumbersome in manufacture, maintenance and in operation through the full range of speed reductions required. In U.S. Pat. No. 4,334,440 filed on Mar. 10, 1980 by H. Fouch and issued June 13, 1982, a continuously varying transmission which employs three sets of gears is disclosed. Here, a means is provided to hold planet gears of a second set of gears against rotation about a sun gear of the second set, but allowing said planet gears to rotate in position. Also, a primary rotary means provides input to a ring gear of the first set while a secondary rotary means is connected to planet gears of a third set of gears to be rotated and provide output while sun gears of the first and third sets are typically interconnected by a shaft extending through a sun gear of the second set.
In the present invention, there is a first planetary group comprising of at least three pairs of planets connected together by a control carrier structure operably meshed around control and driven sun gears. The driven sun gear interconnects with a ring gear which is part of a secondary planetary set which in turn operably houses a plurality of planets, interconnected by a driving carrier structure, meshing and surrounding a sun gear which is operably joined to a load, driven or output shaft. The control and driven sun gears, having equal radii operably joined to a common axis and spaced-apart in parallel from each other. A braking control or speed control device gradually locks the planet control carrier to permit a one-to-one ratio (i.e., wherein the first and secondary planetary sets rotate as a single unit) to a gradually zero-to-one ratio between the first and secondary planetary sets.
It is therefore an object of the present invention to provide an improved continuously variable mechanical transmission system wherein a load gear operably connected to an output or driven shaft rotates and follows a rotating control carrier at a continuously and variably reducing operation.
It is another object of the present invention to provide an improved continuously variable mechanical transmission system wherein the rotation or operation of the control carrier is gradually locked by externally operated brakes, thereby overcoming the locking action between the control carrier and plurality of planet gears to permit reduction of said control carrier and plurality of planet gears at their distinct and separate angular velocities relative to their individual axis, as desired.
It is still another object of the present invention to provide an improved continuously variable mechanical transmission system wherein the braking device in its simple mechanical operation and construction bears minimal load sufficient only to overcome the friction between the meshing gears inherent in the operation of the first planetary set.
It is a further object of the present invention to provide an improved continuously variable mechanical transmission system which can be easily and economically produced, yet sturdy in construction and highly efficient in operation.
It is a further object of the present invention to provide an improved continuously variable mechanical transmission system which is constructed with relative simplicity, embodying relatively simple parts, and therefore capable of being retailed for a low price, long-lasting in use, and extremely convenient to operate.